I've always been partial to Trojans and Interstate makes good ones as well. But you want the heaviest (thickest plates), you can get in a pure deep cycle. If the battery doesn't weigh at least 65 lbs keep shopping. I take it you are certain yours are toast (having tested them). Check your cables for corrosion and wear. Most golf cart manufacturers put cheap/cheesey cables - as in #6 welding cables and they are very inefficient. If you need to replace them upgrade to #4, preferably multi strand tinned Marine grade. You will nearly double the range of your cart. After driving your cart a few miles feel the cables, they will probably be warm or hot to the touch. That heat is generated by the inefficient (as in too small), cables and that energy is not getting to the motor, hence the advisability of increasing the cable size/efficiency. I can play 36 to 54 holes of golf in my 1998 Club Car (48 volt), and still not get a warning light from the batteries while most of my neighbors are done after 18 and heading for the charger and hoping they get there. It doesn't cost all that much but makes a big difference